Such a skin treatment device is, e.g., known from the published international patent application WO 2008/001284 A2. Said application discloses a skin treatment device with a laser source and focusing optics. The device creates a focal spot in a dermis layer of the skin to be treated. The power of the laser source and the dimensions of the focal spot are selected such that laser induced optical breakdown (LIOB) affects the skin in order to stimulate re-growth of skin tissue and reduce wrinkles. It is also disclosed to provide image sensors for detecting wrinkles before the laser light is applied to the skin.
The focal point is created at a fixed treatment depth, somewhere between 0.2 and 2.0 mm. This depth is selected based on the typical composition of human skin. In some cases, however, the optimal treatment depth may be different. The optimal treatment depth depends on, e.g., the thickness of the stratum corneum and the epidermis. If superficial lesions are created above the dermis, micro-rupturing of capillaries may cause petechiae or other adverse side effects may occur. This will lead to an increased social down time. Furthermore, treatment at a non-optimal depth is detrimental to the efficacy of the treatment.
If the light induced damages are selectively created in the collagen fibers of the dermis, the efficacy of the treatment can be increased with a minimum of side effects.